Monsoon to be below normal, says Skymet

Skymet Weather has predicted "below normal" rainfall during the June to September monsoon season due to a strengthening El Niño.

Private met forecaster Skymet Weather has forecast “below normal” rainfall during the monsoon season between June and September, attributing the deficiency to a strengthening El Nino phenomenon.

Monsoon rainfall, the lifeline of agriculture in many states, is expected to be “below normal” to the tune of 94% (with an error margin of +/-5%) of the long-period average (LPA) of 86.86 cm for the 4-month period (REUTERS)

Monsoon rainfall, the lifeline of agriculture in many states, is expected to be “below normal” to the tune of 94% (with an error margin of +/-5%) of the long-period average (LPA) of 86.86 cm for the 4-month period.

There is a 40% chance of “below normal” rainfall (seasonal rainfall that is between 90 to 95% of LPA) during the season; 25% chance of normal rainfall (seasonal rainfall that is between 96 to 104% of LPA); 15% chance of above normal (seasonal rainfall that is between 105 to 110% of LPA); and 0% chance of excess (seasonal rainfall that is more than 110% of LPA) according to Skymet Weather.

According to Skymet Weather, monsoon rainfall is likely to be 99% of LPA in June; 95% of LPA in July; 92% in August and 90% of LPA in September. LPA is the average rainfall between 1971 and 2020.

According to India’s agriculture ministry, 51% of India’s farmed area, accounting for 40% of production, is rain-fed, making the monsoon critical. With 47% of the country’s population dependant on agriculture for their livelihood (according to this year’s Economic Survey), a bountiful monsoon has a direct correlation with a healthy rural economy.

The annual monsoon forecast, therefore, is widely anticipated. Both Skymet and IMD issue multiple forecasts with the April one being the first.

To be sure, Skymet’s first monsoon forecasts of monsoon rainfall for the past five years have differed from the actual rainfall by 4-16% of LPA. For instance, the forecaster said monsoon rainfall would be 98% of LPA in 2022 when the actual rainfall was 106%. IMD’s recent first forecasts of monsoon have roughly the same accuracy as Skymet’s, different from actual rain by 7-13% of LPA since 2018.

IMD follows different categorisations for rainfall measurements in meteorological regions and for all India measurements.

Part of the reason why early forecasts get it wrong is the distance from the time for which the forecast is made. Small errors in measurements fed into forecast models can become large errors for periods further away from the day on which the model is being run. All forecasts are more accurate closer to the event.

This year, Skymet’s forecast factors in an evolving El Nino condition, characterised by an unusual warming of waters in the eastern equatorial Pacific, which has a high correlation with warmer summers and weaker monsoon rains in India.

“Neutral ENSO (El Nino Southern Oscillation) conditions are prevailing at the moment but an evolving El Nino can be seen which will strengthen during the second half of monsoon when rainfall deficiency is likely to increase. It will start with a moderate El Nino during the first couple of months but progress to a strong El Nino during August and September. Our forecasts have accordingly shown a progressive decline in rainfall during the season. Central and northwest India are expected to report a higher deficiency in rainfall compared to other parts. Rajasthan, parts of Gujarat and western parts of Madhya Pradesh are vulnerable to below normal rainfall. There will be occasional good or heavy spells of rainfall due to development of low-pressure systems over Bay of Bengal. This forecast indicates the average picture of rainfall for the season,” explained Mahesh Palawat, vice president, climate and meteorology at Skymet Weather.

Below normal rains are expected to lead to higher temperatures during monsoon. “Temperatures are expected to be above normal. There may be discomfort associated with less rain and heat. During May and June heat waves are expected but higher temperatures may prolong through monsoon season,” Palawat added.

The monsoon is likely to see deficient rains (20 to 59% less than LPA for that meteorological region) in the western and northern parts of the country; below normal (on the lower side of +/-19% according to Skymet) rains in central and eastern parts; and normal rain (+/19% of LPA for that meteorological region) in Peninsular India except Kerala and Coastal Karnataka. According to Skymet there is a 48% probability of El Nino conditions establishing themselves in May, June and July; 64% in June, July, and August; and 67% in July, August, September.

Essentially, El Nino is expected to intensify over the monsoon months. This is in keeping with IMD’s own assessment of the phenomenon.

According to an ENSO bulletin for March issued by IMD, there is 40% probability of El Nino conditions in June, July August which increases to nearly 70% in July, August, September.

Skymet said the agriculture bowl of Punjab, Haryana, Rajasthan, and Uttar Pradesh are likely to get less than normal rains during the second half of the season. For example, in July below normal rains are likely in Gujarat, Rajasthan, Madhya Pradesh, Maharashtra and the west coast. In August, deficient rains are likely over Gujarat, Rajasthan, Madhya Pradesh, Punjab and Haryana. In September, monsoon is expected to withdraw from Rajasthan, Punjab and Haryana and below normal rains are expected over Gujarat, Maharashtra and Madhya Pradesh.

IMD’s forecast this week too will be influenced by its assessment of El Nino.

“We are considering various factors including El Nino probability based on different models. It will be premature for me to comment immediately because various assessments are being made,” said M Ravichandran, secretary, ministry of earth sciences. IMD is expected to announce its long-range forecast for monsoon on Tuesday.

“All we can say is there have been three good monsoon years consecutively. With El Nino we may not see a bounty of rain or an excess rain year. Whether it will be a normal or below normal monsoon year will be known later in April or May,” Ravichandran had said on March 7.

The monsoon is especially crucial for summer crops as it brings about 70% of India’s annual rainfall. It is crucial to one of the mainstays of India’s economy, agriculture. Monsoon spurs farm produce and improves rural spending besides impacting inflation, jobs, and industrial demand. Good farm output keeps food inflation under check and ample harvests raise rural incomes and help inject demand into the economy.

Skymet said southwest monsoon was above normal and normal for the last four consecutive seasons because of Triple-Dip La Niña. “Now, La Niña has ended. Key oceanic and atmospheric variables are consistent with ENSO [El Niño-Southern Oscillation]-neutral conditions. The likelihood of El Niño is increasing, and its probability to become a dominant category during the monsoon is growing large. El Niño return may presage a weaker monsoon,” said Skymet managing director Jatin Singh.

La Nina is the opposite of El Nino and is characterised by cooler currents in the equatorial eastern Pacific.

Skymet said other factors too were influencing the monsoon besides El Niño. “Indian Ocean Dipole (IOD) has the potential to steer monsoon and negate the ill effects of El Niño when sufficiently strong. IOD is neutral now and is leaning to turn moderately positive at the start of the monsoon. El Niño and IOD are likely to be ‘out of phase’ and may lead to extreme variability in the monthly rainfall distribution.”

IOD refers to the temperature differential between the western and eastern Indian Oceans. A positive IOD has a direct correlation with a good monsoon.